Noisy Response-Based Cryptographic Subkeys
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Solution Overview
Problem
Storing and distributing cryptographic keys in terminal devices located in untrusted environments is risky due to vulnerabilities such as replays, man-in-the-middle attacks, and side channel analysis, especially in noisy or hostile environments where error correction methods require heavy processor loads and disclose useful information to attackers.
Innovation Solution
The proposed solution involves building challenge-response-pair (CRP) mechanisms from the message digests of digital files, using one-time use keys for each transaction, and generating keys from the message digest of each file. This approach allows for rapid verification of digital file authenticity and decryption, even in noisy environments, without relying on Error Correcting Codes (ECC) or fuzzy extractors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error correction methods (ECC, fuzzy extractors, data helpers) are used to distribute cryptographic keys in noisy environments, then key distribution reliability is improved, but device complexity and processor load increase significantly
Solution Approach 1:
The patent extracts the error correction functionality from traditional heavy-weight ECC and fuzzy extractor systems, replacing them with a streamlined challenge-response mechanism that inherently tolerates noise through cryptographic design rather than computational correction
Solution Approach 2:
The patent replaces the mechanical/computational error correction systems (ECC codes, fuzzy extractors) with a cryptographic substitution approach where challenge-response pairs provide inherent noise tolerance through their mathematical properties, eliminating the need for heavy processor-based correction mechanisms
2Reliability
If error correction methods (ECC, fuzzy extractors, data helpers) are used to distribute cryptographic keys, then key distribution reliability is improved, but information leakage to attackers increases
Solution Approach 1:
The patent converts the presence of noise and potential information leakage into a benefit by designing a challenge-response system where the noise actually masks the cryptographic interactions, making it harder for attackers to extract useful information while the legitimate parties can still verify authenticity
Solution Approach 2:
The patent introduces challenge-response pairs as an intermediary mechanism that mediates between the noisy communication channel and the cryptographic key distribution, allowing reliable key establishment without directly exposing sensitive information through error correction processes
3Ease of operation
If cryptographic keys are stored in terminal devices in untrusted environments, then decryption capability is improved, but security against attacks (replays, man-in-the-middle, side channel analysis) deteriorates
Solution Approach 1:
The patent performs preliminary generation of challenge-response pairs during an enrollment phase, storing only the responses in the terminal device while keeping challenges secure elsewhere. This preliminary action enables the device to prove possession of keys without storing the keys themselves, maintaining decryption capability while enhancing security
Solution Approach 2:
The patent creates a functional copy of the key possession proof through challenge-response mechanisms, where the terminal device can demonstrate it holds the correct keys by generating valid responses without actually storing or transmitting the private keys, thus enabling decryption capability while preventing key exposure
Data Source
AI summary
Methods for the storage and retrieval of a digital file are disclosed. The file is encrypted with a random binary key. A mathematical CRP mechanism is used to generate an ordered list of responses from a list of challenges. A subset of responses within the ordered list of responses is selected, which each selected response occupying a position in the ordered list that is the same position as a first binary symbol in the random key. In this way, the key can be encoded in the selection of responses. To recover the key, the selected responses are compared to a full list of responses to determine which of the responses in the full list match selected responses. Matches indicate the first binary symbol in the corresponding position in the key and non-matches indicate the second binary symbol. In this way, the key is reconstructed, and file may be decrypted.